The purpose of this contract is: To determine if influenza, mumps and Western equine encephalitis (WEE) viruses can be transmitted from the blood of the pregnant Rhesus monkey to the fetus. To determine if influenza, mumps and WEE viruses can be transmitted to the fetus when inoculated into the amniotic sac. These studies will only be conducted in the event that the virus cannot be transmitted to the fetus by intravenous injection of the pregnant Rhesus monkey. To determine the effects of the influenza, mumps and WEE virus on the fetus when the infection occurs at various stages of gestation.